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Pathways of organic carbon oxidation in three continental margin sedimentsWe have combined several different methodologies to quantify rates of organic carbon mineralization by the various electron acceptors in sediments from the coast of Denmark and Norway. Rates of NH4+ and Sigma CO2 liberation sediment incubations were used with O2 penetration depths to conclude that O2 respiration accounted for only between 3.6-17.4% of the total organic carbon oxidation. Dentrification was limited to a narrow zone just below the depth of O2 penetration, and was not a major carbon oxidation pathway. The processes of Fe reduction, Mn reduction and sulfate reduction dominated organic carbon mineralization, but their relative significance varied depending on the sediment. Where high concentrations of Mn-oxide were found (3-4 wt% Mn), only Mn reduction occurred. With lower Mn oxide concentrations more typical of coastal sediments, Fe reduction and sulfate reduction were most important and of a similar magnitude. Overall, most of the measured O2 flux into the sediment was used to oxidized reduced inorganic species and not organic carbon. We suspect that the importance of O2 respiration in many coastal sediments has been overestimated, whereas metal oxide reduction (both Fe and Mn reduction) has probably been well underestimated.
Document ID
20040089551
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Canfield, D. E.
(Georgia Institute of Technology Atlanta 30332-0340, United States)
Jorgensen, B. B.
Fossing, H.
Glud, R.
Gundersen, J.
Ramsing, N. B.
Thamdrup, B.
Hansen, J. W.
Nielsen, L. P.
Hall, P. O.
Date Acquired
August 21, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Marine geology
Volume: 113
ISSN: 0025-3227
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: NAGW-3117
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
Non-NASA Center

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